Received: March 06, 2020;   Published: May 14, 2020

DOI: 10.32474/AOICS.2020.04.000191

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Abstract

Simple and cost-effective glass sensors for detecting of the hazardous pollutant gases NO₂, formaldehyde and H₂S molecules are qualitatively explored. Porous glass pellets based upon soda lime glass were obtained by crushing, sieving and pressing the grains below 0.075 mm with a filler of soluble salt. The pellets were sintered at 700 °C for 15 min followed by removing of the filler, then dried. The dried pellets are either treated with appropriate reagents such as universal indicator, SnCl₂ or lead acetate for detecting NO₂, formaldehyde or H₂S molecules, respectively. In the case of treatment with universal reagent a red, brownish-red or orange coloration reveals the presence of NO₂, formaldehyde or H₂S molecules, respectively. Glass pellets treated with lead acetate turned into brown or blackish brown color indicating the presence of H₂S gas. Pellets treated with SnCl₂ show an increase in the electrical conductivity when subjected to formaldehyde gases or formaldehyde-containing solution. The increase in the electrical conductivity values is proportional to the exposure time of formaldehyde gas or the immersion time in formaldehyde-containing solution. The described method presents a simple, inexpensive and spread-able technique for detecting the NO₂, formaldehyde or H₂S molecules.

Keywords: Nitrogen dioxide, Formaldehyde, hydrogen disulfide, Glass sensors, Hazard compounds

Abstract| Introduction| Experimental| Results and Discussion| Conclusion| Acknowledgement| References|